The present invention relates to a device for transferring cigarette portions from a dual-rod cigarette manufacturing machine to a filter assembly machine.
On dual-rod cigarette manufacturing machines, the two rods, once formed, are fed parallel to each other along a normally horizontal output bed; and, as they travel along the bed, the rods are fed through a cutting station where they are cut transversely into portions of equal length, which continue traveling along the bed in the same direction as the rods.
When producing filter-tipped cigarettes, the cigarette portions are transferred by a transfer device from the bed to a filter assembly machine, the input station of which is normally defined by a drum conveyor positioned with its axis parallel to the rods, and comprising outer axial grooves, each for receiving at least one cigarette portion.
In U.S. Pat. No. 5,255,777, the cigarette portions are transferred from the output bed of the manufacturing machine to the filter assembly machine by means of a transfer device comprising a transfer drum rotating about an axis parallel to the cigarette portions, and a number of pickup units facing the transfer drum and each comprising two seats. Each pickup unit is movable in such a manner as to keep the respective seats parallel to themselves at all times, and to feed the seats along a first and a second path lying in planes perpendicular to the bed and at different distances from the transfer drum; and each pickup unit picks up one cigarette portion of one rod and the corresponding cigarette portion of the other rod, and feeds the two cigarette portions along a portion of said paths and into two adjacent seats formed on the transfer drum.
To receive both the cigarette portions picked up by each pickup unit, one of the seats in each pair of adjacent seats on the transfer drum is fitted to a lever, which is activated by a cam device to vary the distance between the seat and the axis of the transfer drum, and so enable the seat to receive the cigarette portion traveling along the path furthest from the outer surface of the transfer drum.
Once the pair of cigarette portions has been deposited, the lever is withdrawn to bring the seat back onto the outer surface of the transfer drum, which then transfers the cigarette portions to the input drum conveyor of the filter assembly machine.
The above device involves considerable drawbacks on account of the levers, which make the transfer drum mechanically complex and, hence, unreliable and relatively expensive to produce.
In U.S. Pat. No. 5,267,577, pairs of cigarette portions are transferred using a transfer device in which the seats of the pickup units describe a first and a second path similar to those described above. In this case, however, the transfer conveyor comprises a first and a second drum comprising respective seats for receiving the cigarette portions. More specifically, the first drum is in the form of a cage rotating about a first axis and about the second drum, which rotates about a second axis separated from the first axis by such a distance that the seats of the first and second drums respectively describe a third and a fourth circular path. The two paths are respectively tangent to the first and second paths to receive the cigarette portions from each pickup unit, and are also tangent to each other at a point in which the third and fourth paths are tangent to the input drum conveyor of the filter assembly machine.
The above transfer device provides for effectively transferring pairs of cigarette portions from the bed of a manufacturing machine to the input drum conveyor of a filter assembly machine, but has the disadvantage of comprising a high-cost, structurally complex transfer drum.